This invention relates generally to refrigeration systems and, in particular, the means to sense the ice thickness.
In some refrigeration systems a layer of ice tends to build-up on certain components, and this build-up may not be desirable, depending on the purpose of the system. For example, some air-conditioning systems, dairy cooling systems and other systems wherein constant cooling is required employ a latent heat storage tank wherein ice build-up is desired. A typical latent heat storage tank comprises evaporator coils or tubes which are submerged in water in the tank and on which a layer of ice builds up in response to circulation through the tubes of refrigerant supplied through a condenser from a motor-driven compressor. The refrigerant is then returned from the evaporator to the compressor for recirculation. Typically, the evaporator tubes are on the order of about one-half inch in outside diameter and the thickness of the layer of ice which forms on the exterior of each tube may be as much as one inch thick, measured from exterior surface to the tube to the outer surface of the ice layer. To maintain proper and efficient operation of the system, it is necessary to maintain the thickness of the ice layer within some specified preferred range and this is usually accomplished by intermittently operating the compressor at certain intervals for certain periods of time. This intermittent operation can be accomplished manually by a human operator in response to his visual check of the amount of ice build-up or can be accomplished automatically by compressor control systems which employ devices which sense and measure ice build-up and control compressor operation accordingly. The following U.S. Patents illustrate some such prior art control systems: U.S. Pat. Nos. 3,552,136 Cook; 3,898,856 Komedera; 3,360,951 Hoenisch; 2,076,119 Carraway; 2,867,092 Perry; 2,624,180 Grimshaw; 2,622,923 Cobb; 3,672,183 Bernstein; 4,011,733 Kuckens; 3,484,805 Lorenz; 2,187,258 Wood; 3,127,486 Blumenshine; 1,916,315 Hoffman; 2,448,453 Morrison.